4R Nutrient management

When it comes to fertilizing crops, maximizing nutrient uptake and minimizing losses is what it’s all about. The ability to capture a greater fraction of applied nutrients in your crops increases nutrient efficiency and most importantly, your bottom line. Right source. Right rate. Right time. Right place. These are the four R’s of ‘4R nutrient management’

4R Nutrient management is a concept promoted by the Fertilizer Institute, the Canadian Fertilizer Institute, the International Plant Nutrition Institute, and the International Fertilizer Industry to encourage farmers and Certified Crop Advisors to practice better fertility management. In addition to these organizations, land grant universities, consultants, and some agricultural industries are supporting 4R nutrient management.

The 4R’s are simple, common sense rules backed by research and science-based principles that support high-yielding, high-quality crop production while improving soil quality and reducing nutrient loss to the environment.

Right source

Selecting the right nutrient source starts by knowing what’s in the soil, so step one is taking a good soil sample and getting the proper analysis done. Knowing the amount of plant-available P and K will dictate what fertilizer blends you will need and how much. If manure is in abundant supply, remember that P and K availability of manure is close to that of fertilizer.

Right time

The right time means synchronizing nutrient applications with crop uptake. A good example of this is nitrogen (N) application on corn. Gone are the days of putting on all of a corn crop’s N needs ‘upfront’or prior to planting, and the reason why is simple: Applying all N before the crop is growing is extremely inefficient. Today, applying ~20 lb/ac of N through the planter and sidedressing the remainder of the N just prior to the maximum N uptake period is a routine practice on many farms. Soil N tests (e.g, PSNT and ISNT) and tools like the Adapt-N model are helpful for fine-tuning the timing and amount of sidedress N.

Right place

The right place implies keeping crop nutrients where they can be utilized. A good example of this is incorporating manure. Manure incorporation mixes manure nutrients into the soil where crop roots have a greater chance to utilize them, as opposed to leaving manure on the surface where it is subject to runoff losses and volatilization. In just a week’s time, for example, the ammonia-N fraction of manure is nearly gone if not incorporated. Other good examples include any practices that help to reduce soil erosion (e.g., reduced-tillage, cover crops, tile-drainage, buffer strips). Lowering erosion means keeping more of your precious topsoil in place, the place where nutrients, organic matter, and soil life are concentrated.

Right rate

The concept here is deceptively simple— apply crop nutrients at a level that maximizes the chance for an economically optimum yield (EOY). While this may sound simple in concept, the complexities of weather, soils, and operational logistics on nutrient availability are very real. Utilize Land Grant university recommendations, as they are designed to produce an EOY. Other important practices include good record keeping, manure testing, nutrient balance calculations, variable rate application technology, N testing (e.g., corn stalk nitrate test, soil N tests) and N modeling tools.